The University of Melbourne study surveyed more than 8000 teachers and many say that weeks of preparation for testing are taking a toll on students.

"You're looking at a figure of... about 90 per cent of teachers who have actually had between one and 10 students come to them and say 'I'm feeling stressed' or 'I have a headache'", Lead researcher Nicky Dulfer told Adam Spencer.

"We told teachers that we wanted them to report only on things that students had said to them, they weren't allowed to say I've noticed, it had to be reported to them; and that's quite alarming, if you put that across the whole nation."

Mrs Dulfer found that most consider the tests to be a way of ranking schools.

"A lot of teachers do believe it is a school ranking tool and that it's a method of policing school performance," she said.

This belief is igniting paranoia among teachers, with almost half those surveyed reporting that they're preparing students regularly for the tests; months in advance.

"One of the things that came through very strongly and was a bit of a surprise for all of us I think, was the amount of time that teachers are spending practicing for NAPLAN," Mrs Dulfer told Adam Spencer.

"Forty-six per cent of our teachers reported that they are practicing for NAPLAN, five months out, every single week, they're practicing it, and that's an astonishing thing...

"According to them what's happening is that it's reduced the importance of other curriculum areas and it means that they're not spending face to face time with their students, and certain subjects like the arts [and] languages are actually facing time table reductions."